Why are you asking this question in April when you have to wait until October anyways? You should have at least waited until the end of Sept to ask. So many things could happen between now and then that could/would change everyone's opinion.
Personally, if a new iMac doesn't come out by October I would wait until Apple does come out with a new one. By then the current iMacs will be 7 months old and an update would be just around the corner.